Boy Wonder

In the above grid, the 5 letter words to the left are guesses offered to see how closely they match a 5 letter mystery word of non-repeating letters (minus J, Q, X and Z).  The numbers on the right indicate how many letters in each guess are in the mystery word and in the correct position (the green squares); how many are in the word but in an incorrect position (the yellow squares); and how many are not in the word at all (red squares).  The letters in white in the keyboard configuration below the grid have not been guessed.  I have blanked out the puzzle's answer in case you would like to try your hand at guessing based on the clues, but-- spoiler alert!-- it is revealed without warning in the text that follows.

Tonight's Word500 was particularly challenging.  I entered my favorite openers (FLUID, GHOST, CREAM) and getting only one letter in each word, I immediately knew I was in trouble.  On the good chance that I could eliminate some letters off the bat, I next tried GHOUL, but that only deepened the quagmire.  My first 7 words eluded my attempts to eliminate any letters, and then I was faced with a real puzzle.  All I knew was that the answer, a 5 letter English word with no repeating letters contained 3 letters (1 each) from FLUID GHOST and CREAM and 2 more that I had not yet tried.  I was able to solve it eventually through a process of elimination (E, T, U, L, S, F were the first to fall followed much later by H) after which things began to fall rapidly into place and I was able to guess the first word I could find which fit all the patterns-- ROBIN-- and it was correct.  Since tonight's was a particularly challenging and ultimately satisfying solve, I was curious what AI would make of it.  I composed my question and posed it to Google's AI Mode.

For a word guessing game in which the answer is a 5 letter word with no repeating letters (and no J, Q, X or Z in the word), the player guesses a 5 letter word and is told how many of the letters in the test word are in the answer in the right position, how many are in the wrong position and how many are not in the word at all.  The player is given 8 guesses.   The first 7 guesses in tonight’s game with their results are as follows:

FLUID (1 letter in the correct position, 4 letters not in the word)

GHOST (1 letter in the incorrect position, 4 letters not in the word)

CREAM (1 letter in the incorrect position, 4 letters not in the word)

GHOUL (1 letter in the incorrect position, 4 letters not in the word)

FETID (1 letter in the correct position, 4 letters not in the word)

MARCH (1 letter in the incorrect position, 4 letters not in the word)

PERCH (1 letter in the incorrect position, 4 letters not in the word)

You have one more guess and it must be the answer.  What are possible answers?

AI churned for quite a long time, updating the status with "Taking more time to think..." until finally the following answer was returned: 

Something went wrong and an AI response wasn't generated.

I asked, "Are you missing information or not understanding the question? What went wrong?"   AI took as long again as the first attempt-- more than a minute each time-- and finally popped back with the answer:

ROBIN is the only common English word that logically fits all seven clues. 

Deduction Breakdown 

1 Find the Green (Correct Position) Letter:  FLUID and FETID both have exactly one letter in the correct position.  They share the letters F (position 1), I (position 4), and D (position 5).  If F or D were correct, then the other letters of both words would be completely excluded. However, testing those letters eliminates too many possibilities required by the other clues.  If I is the correct letter in position 4 (_ _ _ I _), it perfectly satisfies both clues, meaning F, L, U, D, E, and T are completely excluded. 

2 Isolate the Yellow (Incorrect Position) Letters:  MARCH and PERCH both give exactly one yellow letter. Since E is already excluded, they share the string RCH in positions 3, 4, and 5.  Since position 4 is occupied by I, C cannot be the yellow letter. This leaves either R or H as the valid letter.  If we look at CREAM (which also gives one yellow letter), the letter R satisfies this perfectly. Therefore, R is in the word but not in position 2 (CREAM) or position 3 (MARCH/PERCH). This leaves position 1 (R _ _ I _).  Since R is our yellow letter for those words, M, A, P, C, and H are excluded. 

3 Fill the Remaining Spaces:  GHOST and GHOUL both give exactly one yellow letter. Since H, S, T, U, and L are now excluded, the yellow letter they share must be O.  In GHOST and GHOUL, O is in position 3, so it cannot be there in the final answer. Placing it in position 2 gives us R O _ I _.The remaining constraints leave only a few valid consonants (like B, K, N, V, W, Y) to fill positions 3 and 5. 

Combining these constraints to form a valid, non-repeating 5-letter English word gives ROBIN.

So what went wrong the first time?  Per AI mode:

It is a fantastic logic puzzle! I apologize for the initial hiccup—sometimes analyzing overlapping constraints simultaneously can cause an AI to get stuck in an internal loop before generating a response.  Once the constraints are properly mapped, the elimination process flows smoothly. It's the kind of puzzle where finding that first breakthrough (like realizing I is locked into the 4th position from FLUID and FETID) completely shatters the problem wide open.

My process was almost entirely letter elimination via logic, with a bit of trial and error to eliminate stubborn contenders like the F in FLUID and FETID thrown in.  When I had reached a critical mass with my letter elimination, I was able to float words composed from the handful of remaining letters to find my answer.  Not outrageously unlike AI's description of its process although mine was a bit more piecemeal especially in the beginning.  Comparing notes, I observed that whereas AI's approach moved forward from FLUID, my strategy after I had found myself unable to eliminate any letters automatically with my guesses or to unambiguously identify enough correct letters in correct places was to work backward from PERCH. 

I had to ask AI Mode if their answer was deduced or if it had been found on the web (no judgment!), and in either case if they could shed some light on the black box of AI's workings.  The answer was that it was definitely deduced through straightforward classic computation.  I was convinced.  

I apologize for any resources destroyed in the satisfaction of my curiosity.